Preparation process of fiber multi-layer shaving board

Abstract

The invention provides a preparation process of a fiber multi-layer shaving board, and relates to the technical field of shaving board preparation, the preparation process comprises the following steps: S1, preparing materials; s2, preparing fibers; s3, drying and sorting; s4, mixing and applying glue; s5, paving and forming; s6, compression molding; s7, carrying out post-treatment; and S8, performing automatic storage. One-time paving and hot-press forming are adopted to replace a traditional secondary fiberboard pressing and pasting technology, the secondary processing link is avoided, the production efficiency is improved, secondary uneven distribution of glue and thermal degradation are avoided, the problems of degumming, deformation and cracking are fundamentally eliminated, the service life of the product is prolonged, the supporting force is guaranteed through the multi-layer symmetrical structure and the core layer coarse wood shavings, and the service life of the product is prolonged. The secondary surface layer and the fine surface layer are transited, the fiber surface layer is enhanced and combined, and precise sizing is matched, so that the static bending strength and the internal bonding strength of the product exceed the standard of a traditional shaving board.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of particleboard preparation, and in particular to a preparation process of a fiber multi-layer particleboard. Background Art

[0002] As one of the core categories in the field of artificial boards, particleboard has been widely used in furniture manufacturing, architectural decoration, interior decoration and other fields due to its advantages such as high raw material utilization, moderate production cost and relatively uniform structure. Its core usage requirements are concentrated in four dimensions: surface quality, structural strength, processing adaptability and long-term use stability.

[0003] Currently, mainstream particleboard production in the industry mostly utilizes a three-layer structure consisting of an upper layer, a core layer, and a lower layer. The raw material is primarily wood shavings, which exposes numerous inherent flaws in actual production and application. In terms of surface quality, traditional particleboard uses wood shavings directly for both the upper and lower layers. The gaps between the shavings result in poor surface flatness and a low finish, making it unable to directly meet the requirements of high-end secondary finishing processes such as PET veneer, UV coating, milling and engraving, and electrostatic spraying. Furthermore, if used for furniture panels or exterior structural components, additional surface treatment is required, significantly increasing production cycle time and costs.

[0004] From the perspective of bonding stability, in traditional processes, adhesives are often directly mixed with wood chips before paving. Affected by the shape of the wood chips, the uniformity of the glue application, and the pressing process, the adhesive tends to accumulate or overflow at the edge of the slab, resulting in edge degumming and delamination of the board after pressing. The degumming problem is especially obvious after the board is cut and processed, which directly reduces the product qualification rate and service life. In order to improve the surface performance, some manufacturers have tried to adopt a processing model of particleboard substrate and secondary pressing fiberboard, that is, first producing ordinary particleboard, and then pressing an additional layer of fiberboard on its surface to improve the flatness. However, this process has significant disadvantages: the secondary pressing process requires re-gluing and heating, which on the one hand can easily lead to uneven secondary distribution of the adhesive and form local weak bonding areas; on the other hand, the glue is prone to thermal degradation after being heated twice, which reduces the bonding strength, and then causes quality problems such as degumming, deformation, and cracking during the use of the product. This not only increases the production process and energy consumption, but also makes it difficult to ensure the quality consistency of batch products. Summary of the Invention

[0005] 1. Technical problem to be solved by the invention: The present invention provides a preparation process of a fiber multi-layer particleboard, which is used to solve the technical problems existing in the above background technology.

[0006] 2. Technical solution: To achieve the above object, the present invention provides a technical solution: a process for preparing a fiber multilayer particleboard, comprising the following steps: S1. Material preparation: preparing wood raw materials and fiber raw materials; the wood raw materials are used to prepare core shavings, sub-surface shavings and fine surface shavings, and the fiber raw materials are wood fibers or plant fibers; S2, fiber preparation: feeding the fiber raw material in step S1 into a grinder for grinding, and screening through a 120-220 mesh screen after grinding to remove impurities and insufficiently ground crude fibers to obtain qualified fiber material; S3. Drying and sorting: S301. Feed the core wood shavings, sub-surface wood shavings and fine surface wood shavings prepared in step S1 into a dryer for drying, respectively, and control the moisture content of the wood shavings after drying to be 1.5-2.8%; S302, sending the qualified fiber material obtained in step S2 into a fiber dryer for drying, and controlling the moisture content of the fiber material after drying to be 1.2-2.5%; S303, screening the dried core shavings, sub-surface shavings and fine surface shavings through a grading screen to remove core shavings with a length of less than 50 mm, sub-surface shavings and fine surface shavings with a length of less than 30 mm; S4, glue application: S401, sizing the core wood shavings: adding isocyanate glue to the dried core wood shavings in an amount of 6-9% based on the dry weight of the core wood shavings, and stirring evenly; S402, sizing the sub-surface wood chips and the fine surface wood chips: adding melamine urea-formaldehyde resin glue to the dried sub-surface wood chips and the fine surface wood chips, respectively, in an amount of 7-12% based on the dry weight of the sub-surface wood chips or the fine surface wood chips, and controlling the moisture content of the wood chips after sizing to be 6-11%, and stirring evenly; S403, sizing the fiber material: adding modified urea-formaldehyde resin glue to the dried qualified fiber material, wherein the modified urea-formaldehyde resin glue comprises 9-13 parts by weight of urea-formaldehyde resin, 1.5-3.5 parts by weight of polyvinyl alcohol, 0.8-1.8 parts by weight of waterproofing agent, and 6-9 parts by weight of distilled water, with the glue amount being 9-13% based on the dry weight of the fiber material, and stirring uniformly; S5. Paving and forming: A paving device is used to continuously pave a multi-layer slab on a conveyor belt at one time. The center of the multi-layer slab is a core layer. A sub-surface layer, a fine surface layer, and a fiber surface layer are symmetrically arranged on the upper and lower sides of the core layer. The fiber surface layer has a thickness of 1.1 to 1.5 mm, the fine surface layer has a thickness of 1.8 to 3.5 mm, the sub-surface layer has a thickness of 3.5 to 5.5 mm, and the core layer has a thickness of 8.5 to 15.5 mm. S6, compression molding: S601, pre-pressing: feeding the multi-layer slab from step S5 into a pre-pressing machine, and pre-pressing for 2.5 to 6 minutes at a pressure of 1.2 to 3.5 MPa and a temperature of 35 to 50° C. to obtain a pre-pressed body; S602, hot pressing: the pre-pressed green body is fed into a continuous flat press at once, and hot pressed for 3.5 to 9 minutes at a pressure of 4.5 to 6.5 MPa and a temperature of 185 to 225°C. During the hot pressing process, the green body density is controlled to be 680 to 780 kg / m³, to obtain a formed plate; S7, post-processing: S701, Sanding: Sand both sides of the hot-pressed sheet to remove surface burrs and uneven areas, and control the thickness deviation of the sheet after sanding to ≤±0.25mm; S702, cutting: according to the finished product size requirements, the sanded plate is cut to length; S703, Surface treatment: Dust and oil removal are carried out on the surface of the cut plate, and UV coating roller coating process is used to make the surface of the plate high glossy; S8, automatic storage: the plate materials processed in step S7 are subjected to quality inspection, and those that pass the inspection are sent to the automatic storage system for classification and storage.

[0007] Preferably, in step S1, the core layer shavings have a length of 120 mm to 160 mm, a width of 15 mm to 35 mm, and a thickness of 0.5 mm to 0.9 mm; the sub-surface shavings and fine surface shavings have a length of 60 mm to 110 mm, a width of 8 mm to 20 mm, and a thickness of 0.3 mm to 0.6 mm.

[0008] Preferably, in step S2, the grinder is a double-disc grinder, the grinding disc gap is controlled to be 0.15-0.35 mm during grinding, and the grinding speed is 1300-1600 r / min; in step S301, the dryer is a mesh belt dryer, the drying temperature is 105-125°C, and the drying time is 18-28 min; in step S302, the fiber dryer is an air flow dryer, the drying temperature is 85-105°C, and the drying time is 6-12 min.

[0009] Preferably, in step S403, the waterproofing agent is a paraffin emulsion, and the solid content of the modified urea-formaldehyde resin glue is 42-47%; in step S4, a double-shaft stirrer is used for stirring, the stirring speed is 350-550 r / min, and the stirring time is 3.5-5.5 min to ensure that the adhesive evenly covers the wood shavings or fiber material.

[0010] Preferably, in step S5, the paving speed of the paving system matches the feeding speed of the continuous flatbed press and is controlled to be 5.5 to 8.5 m / min.

[0011] Preferably, in step S602, the continuous flat press adopts segmented temperature control, with the temperature of the front section of hot pressing being 185-195°C, the temperature of the middle section being 195-215°C, and the temperature of the back section being 215-225°C.

[0012] Preferably, in step S703, the UV coating roller coating process includes the following steps: S7031, first roller coating of UV primer; S7032, UV curing, curing time 12 to 22 seconds, UV intensity 85 to 125 mW / cm²; S7033, sanding; S7034, secondary roller coating UV topcoat; S7035, UV curing, curing time 22 ~ 32s, UV intensity 125 ~ 155mW / cm², forming a high gloss coating with a thickness of 0.15 ~ 0.35mm.

[0013] 3.Beneficial effects: Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The present invention adopts one-time paving and hot pressing to replace the traditional secondary pressing fiberboard process, avoiding the secondary uneven distribution of glue and thermal degradation, eliminating the problems of degumming, deformation and cracking from the root, and improving the service life of the product. The multi-layer symmetrical structure of the present invention, the coarse wood particles in the core layer to ensure the supporting force, the transition between the sub-surface layer and the fine surface layer, the enhanced bonding of the fiber surface layer, and the precise gluing make the product's static bending strength and internal bonding strength exceed the traditional particleboard standard.

[0014] The present invention optimizes the surface quality. The fiber surface of the present invention is combined with the UV high-gloss process. The ordinary fiber surface Ra is ≤ 1.8μm and the high-gloss surface Ra is ≤ 0.7μm. It can directly meet the high-end decoration needs such as PET veneer and electrostatic spraying without additional surface treatment.

[0015] The present invention's continuous paving and pressing systems work together to avoid secondary processing, improving production efficiency and raw material utilization, fully utilizing fine wood shavings and fiber, achieving both economic and environmental benefits. This invention removes unqualified wood shavings through graded screening, controls moisture content fluctuations through precise drying, and uses staged hot pressing to minimize the product's water absorption and thickness expansion, narrowing the range of quality fluctuations and ensuring product stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0017] To facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "page", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0020] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," "fixed," "provided with," and the like should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0021] It should be noted that the structures not introduced in the present invention are the same as those in the prior art or can be implemented by using the prior art, and are not described in detail here because they do not involve the design points and improvement directions of the present invention.

[0022] Refer to the attached Figure 1 A process for preparing a fiber multilayer particleboard comprises the following steps: S1. Material preparation: preparing wood raw materials and fiber raw materials; the wood raw materials are used to prepare core shavings, sub-surface shavings and fine surface shavings, and the fiber raw materials are wood fibers or plant fibers; S2, fiber preparation: feeding the fiber raw material in step S1 into a grinder for grinding, and screening through a 120-220 mesh screen after grinding to remove impurities and insufficiently ground crude fibers to obtain qualified fiber material; S3. Drying and sorting: S301. Feed the core wood shavings, sub-surface wood shavings and fine surface wood shavings prepared in step S1 into a dryer for drying, respectively, and control the moisture content of the wood shavings after drying to be 1.5-2.8%; S302, sending the qualified fiber material obtained in step S2 into a fiber dryer for drying, and controlling the moisture content of the fiber material after drying to be 1.2-2.5%; S303, screening the dried core shavings, sub-surface shavings and fine surface shavings through a grading screen to remove core shavings with a length of less than 50 mm, sub-surface shavings and fine surface shavings with a length of less than 30 mm; S4, glue application: S401, sizing the core wood shavings: adding isocyanate glue to the dried core wood shavings in an amount of 6-9% based on the dry weight of the core wood shavings, and stirring evenly; S402, sizing the sub-surface wood chips and the fine surface wood chips: adding melamine urea-formaldehyde resin glue to the dried sub-surface wood chips and the fine surface wood chips, respectively, in an amount of 7-12% based on the dry weight of the sub-surface wood chips or the fine surface wood chips, and controlling the moisture content of the wood chips after sizing to be 6-11%, and stirring evenly; S403, sizing the fiber material: adding modified urea-formaldehyde resin glue to the dried qualified fiber material, wherein the modified urea-formaldehyde resin glue comprises 9-13 parts by weight of urea-formaldehyde resin, 1.5-3.5 parts by weight of polyvinyl alcohol, 0.8-1.8 parts by weight of waterproofing agent, and 6-9 parts by weight of distilled water, with the glue amount being 9-13% based on the dry weight of the fiber material, and stirring uniformly; S5. Paving and forming: A paving device is used to continuously pave a multi-layer slab on a conveyor belt at one time. The center of the multi-layer slab is the core layer. The sub-surface layer, fine surface layer and fiber surface layer are symmetrically arranged on the upper and lower sides of the core layer. The fiber surface layer has a thickness of 1.1-1.5 mm, the fine surface layer has a thickness of 1.8-3.5 mm, the sub-surface layer has a thickness of 3.5-5.5 mm, and the core layer has a thickness of 8.5-15.5 mm. S6, compression molding: S601, pre-pressing: feeding the multi-layer slab from step S5 into a pre-pressing machine, and pre-pressing for 2.5 to 6 minutes at a pressure of 1.2 to 3.5 MPa and a temperature of 35 to 50° C. to obtain a pre-pressed body; S602, hot pressing: the pre-pressed green body is fed into a continuous flat press at once, and hot pressed for 3.5 to 9 minutes at a pressure of 4.5 to 6.5 MPa and a temperature of 185 to 225°C. During the hot pressing process, the green body density is controlled to be 680 to 780 kg / m³, to obtain a formed plate; S7, post-processing: S701, Sanding: Sand both sides of the hot-pressed sheet to remove surface burrs and uneven areas, and control the thickness deviation of the sheet after sanding to ≤±0.25mm; S702, cutting: according to the finished product size requirements, the sanded plate is cut to length; S703, Surface treatment: Dust and oil removal are carried out on the surface of the cut plate, and UV coating roller coating process is used to make the surface of the plate high glossy; S8, automatic storage: the plate materials processed in step S7 are subjected to quality inspection, and those that pass the inspection are sent to the automatic storage system for classification and storage.

[0023] In step S1, the core layer shavings have a length of 120 mm to 160 mm, a width of 15 mm to 35 mm, and a thickness of 0.5 mm to 0.9 mm; the sub-surface shavings and fine surface shavings have a length of 60 mm to 110 mm, a width of 8 mm to 20 mm, and a thickness of 0.3 mm to 0.6 mm.

[0024] In step S2, the grinder is a double-disc grinder, and the grinding disc gap is controlled to be 0.15-0.35 mm during grinding, and the grinding speed is 1300-1600 r / min; in step S301, the dryer is a mesh belt dryer, the drying temperature is 105-125°C, and the drying time is 18-28 min; in step S302, the fiber dryer is an air flow dryer, the drying temperature is 85-105°C, and the drying time is 6-12 min.

[0025] In step S403, the waterproofing agent is paraffin emulsion, and the solid content of the modified urea-formaldehyde resin glue is 42-47%; in step S4, a double-shaft stirrer is used for stirring, the stirring speed is 350-550 r / min, and the stirring time is 3.5-5.5 min to ensure that the adhesive evenly covers the wood chips or fiber material.

[0026] In step S5, the paving speed of the paving system is matched with the feeding speed of the continuous flatbed press and is controlled to be 5.5 to 8.5 m / min.

[0027] In step S602, the continuous flat press adopts segmented temperature control, with the temperature of the front section of hot pressing being 185-195°C, the temperature of the middle section being 195-215°C, and the temperature of the back section being 215-225°C.

[0028] In step S703, the UV coating roller coating process includes the following steps: S7031, first roller coating of UV primer; S7032, UV curing, curing time 12 to 22 seconds, UV intensity 85 to 125 mW / cm²; S7033, sanding; S7034, secondary roller coating UV topcoat; S7035, UV curing, curing time 22 ~ 32s, UV intensity 125 ~ 155mW / cm², forming a high gloss coating with a thickness of 0.15 ~ 0.35mm.

[0029] The specific working process is as follows: Raw material pretreatment stage: Wood raw materials are graded and prepared according to core coarse shavings, sub-surface shavings and fine surface shavings to ensure the support of the core layer and the fineness of the surface layer; the fiber raw materials are finely ground and screened to ensure the uniformity and bonding strength of the fiber surface; the drying process is differentially controlled according to the type of raw material to avoid excessive moisture content that causes glue overflow during pressing or too low moisture content that affects bonding.

[0030] Gluing and paving stage: Adhesives are adapted according to the functional requirements of different layers. The core layer isocyanate glue ensures strength, the sub-surface and fine surface layers are made of melamine urea-formaldehyde resin glue to improve weather resistance, and the fiber layer is made of modified urea-formaldehyde resin glue to enhance adhesion. Biaxial stirring is used to ensure uniform coating of the glue liquid. The continuous paving system forms a multi-layer structure in one go according to the principle of coarse to fine and symmetrical distribution to avoid misalignment and gaps between layers.

[0031] Pressing and curing stage: Pre-pressing first fixes the shape of the slab to prevent inter-layer slippage during hot pressing; segmented hot pressing allows the glue to gradually solidify from the outside to the inside, avoiding local overheating that may cause glue degradation, while controlling the density to be uniform and ensuring stable mechanical properties.

[0032] Post-processing and quality inspection stage: Sanding and cutting ensure dimensional accuracy, and the UV process forms a dense high-gloss coating through two-stage curing. The quality inspection link strictly controls key performance to ensure that the product meets the requirements of high-end applications. Finally, qualified products are put into storage to achieve industrialized continuous production.

[0033] Example 1 1. Material preparation: The wood raw materials are processed to prepare core shavings, sub-surface shavings and fine surface shavings. The specifications of the core shavings are 120mm×15mm×0.5mm, the specifications of the sub-surface shavings are 60mm×8mm×0.3mm, and the specifications of the fine surface shavings are 60mm×8mm×0.3mm. The fiber raw material is wood fiber.

[0034] 2. Fiber preparation: The fiber raw materials are ground using a double-disc mill, with the disc gap controlled at 0.15 mm and the grinding speed controlled at 1300 r / min. After grinding, the raw materials are screened through a 120-mesh sieve to remove impurities and insufficiently ground coarse fibers to obtain qualified fiber materials.

[0035] 3. Drying and sorting: Use a mesh belt dryer to dry the wood shavings at a drying temperature of 105°C, a drying time of 18 minutes, and a moisture content of 2.0%; use an air flow dryer to dry qualified fiber materials at a drying temperature of 85°C, a drying time of 6 minutes, and a moisture content of 1.5%; use a grading screen to screen and remove core shavings with a length of less than 55 mm, sub-surface shavings with a length of less than 35 mm, and fine surface shavings.

[0036] 4. Glue adjustment: add isocyanate glue to the core layer wood chips, with a glue amount of 6%; add melamine urea-formaldehyde resin glue to the sub-surface wood chips and fine surface wood chips respectively, with a glue amount of 7%, and the moisture content of the wood chips after gluing is controlled to 6%; add modified urea-formaldehyde resin glue to the qualified fiber material, the modified urea-formaldehyde resin glue consists of 9 parts by weight of urea-formaldehyde resin, 1.5 parts by weight of polyvinyl alcohol, 0.8 parts by weight of paraffin emulsion, and 6 parts by weight of distilled water, with a solid content of 42% and a glue amount of 9%; after gluing, all the above raw materials are stirred with a double-shaft stirrer, with a stirring speed of 350r / min and a stirring time of 3.5min to ensure uniform stirring.

[0037] 5. Paving and forming: The paving speed is controlled at 5.5m / min, and the thickness of each layer of the multi-layer slab is as follows: core layer 8.5mm, sub-surface layer 3.5mm, fine surface layer 1.8mm, and fiber surface layer 1.1mm.

[0038] 6. Pressing: First, pre-pressing treatment is carried out with a pre-pressing pressure of 1.2 MPa, a pre-pressing temperature of 35°C, and a pre-pressing time of 2.5 min to obtain a pre-pressed green body; then the pre-pressed green body is subjected to hot pressing treatment with segmented temperature control at temperatures of 185°C, 195°C, and 215°C, respectively, a hot pressing pressure of 4.5 MPa, and a hot pressing time of 3.5 min. During the hot pressing process, the green body density is controlled at 680 kg / m³ to obtain a formed plate.

[0039] 7. Post-processing: Double-sided sanding of the formed sheet is carried out, and the thickness deviation of the sheet after sanding is controlled within ±0.25mm; UV coating roller coating process is used for high-gloss surface treatment, with the first UV curing time of 12s and UV intensity of 85mW / cm², and the second UV curing time of 22s and UV intensity of 125mW / cm². The thickness of the high-gloss coating formed is 0.15mm.

[0040] 8. Quality inspection and warehousing: The post-processed plates are quality inspected and sent to the automatic storage system for storage after passing the inspection.

[0041] Example 2 1. Material preparation: prepare core shavings, sub-surface shavings and fine surface shavings. The specifications of the core shavings are 140mm×25mm×0.7mm, and the specifications of the sub-surface shavings and fine surface shavings are both 85mm×14mm×0.45mm. Plant fiber is used as the fiber raw material.

[0042] 2. Fiber preparation: The fiber raw material was ground using a double-disc mill with a grinding disc gap of 0.25 mm and a grinding speed of 1450 r / min. After grinding, the raw material was screened through a 170-mesh sieve to remove impurities and insufficiently ground coarse fibers to obtain qualified fiber material.

[0043] 3. Drying and sorting: The wood chips were dried in a mesh belt dryer at a drying temperature of 115°C and a drying time of 23 minutes, with the moisture content of the wood chips controlled at 2.4%. The qualified fiber materials were dried in an air flow dryer at a drying temperature of 95°C and a drying time of 9 minutes, with the moisture content of the fiber controlled at 2.2%.

[0044] 4. Glue application: Apply isocyanate glue to the core layer wood chips with a glue application amount of 7.5%; apply melamine urea-formaldehyde resin glue to the sub-surface wood chips and fine surface wood chips with a glue application amount of 9.5%. After gluing, the moisture content of the wood chips is controlled to be 8.5%; apply modified urea-formaldehyde resin glue to the fiber material. The modified urea-formaldehyde resin glue consists of 11 parts by weight of urea-formaldehyde resin, 2.5 parts by weight of polyvinyl alcohol, 1.3 parts by weight of paraffin emulsion, and 7.5 parts by weight of distilled water, with a solid content of 45% and a glue application amount of 11%. After gluing, stir the raw materials with a double-shaft stirrer at a stirring speed of 450r / min and a stirring time of 4.5min to ensure uniform stirring.

[0045] 5. Paving and forming: The paving speed is 7m / min, and the thickness of each layer of the multi-layer slab is: core layer 12mm, sub-surface layer 4.5mm, fine surface layer 2.6mm, and fiber surface layer 1.3mm.

[0046] 6. Pressing: pre-pressing pressure 2.3MPa, pre-pressing temperature 42℃, pre-pressing time 4.2min; hot pressing temperature control in stages: 190℃, 205℃, 220℃, hot pressing pressure 5.5MPa, hot pressing time 6.2min, slab density controlled at 730kg / m³, to obtain formed sheets.

[0047] 7. Post-treatment: UV coating roller coating process is used, the first UV curing time is 17s, the UV intensity is 105mW / cm², the second UV curing time is 27s, the UV intensity is 140mW / cm², and the high-gloss coating thickness is 0.25mm.

[0048] 8. Quality inspection and warehousing: After passing the quality inspection, the products are sent to the automatic warehousing system for storage.

[0049] Example 3 1. Material preparation: prepare core shavings, sub-surface shavings and fine surface shavings. The specifications of the core shavings are 160mm×35mm×0.9mm, and the specifications of the sub-surface shavings and fine surface shavings are both 110mm×20mm×0.6mm. The fiber raw material is wood fiber.

[0050] 2. Fiber preparation: Grind the fiber raw material with a double-disc mill, with a grinding disc gap of 0.35 mm and a grinding speed of 1600 r / min; after grinding, screen through a 220-mesh sieve to remove impurities and insufficiently ground crude fibers to obtain qualified fiber material.

[0051] 3. Drying and sorting: The wood chips are dried in a mesh belt dryer at a drying temperature of 125°C and a drying time of 28 minutes, and the moisture content of the wood chips is controlled at 2.8%. The qualified fiber materials are dried in an air flow dryer at a drying temperature of 105°C and a drying time of 12 minutes, and the moisture content of the fiber is controlled at 3.0%.

[0052] 4. Glue application: Apply isocyanate glue to the core layer wood chips, with a glue application amount of 9%; apply melamine urea-formaldehyde resin glue to the sub-surface wood chips and fine surface wood chips, with a glue application amount of 12%. After gluing, the moisture content of the wood chips is controlled to be 11%; apply modified urea-formaldehyde resin glue to the fiber material, and the modified urea-formaldehyde resin glue consists of 13 parts by weight of urea-formaldehyde resin, 3.5 parts by weight of polyvinyl alcohol, 1.8 parts by weight of paraffin emulsion, and 9 parts by weight of distilled water, with a solid content of 47% and a glue application amount of 13%; after gluing, stir the raw materials with a double-shaft stirrer at a stirring speed of 550r / min and a stirring time of 5.5min to ensure uniform stirring.

[0053] 5. Paving and forming: The paving speed is 8.5m / min, and the thickness of each layer of the multi-layer slab is: core layer 15.5mm, sub-surface layer 5.5mm, fine surface layer 3.5mm, and fiber surface layer 1.5mm.

[0054] 6. Pressing: pre-pressing pressure 3.5MPa, pre-pressing temperature 50℃, pre-pressing time 6min; hot pressing temperature control in stages: 195℃, 215℃, 225℃, hot pressing pressure 6.5MPa, hot pressing time 9min, slab density controlled at 780kg / m³, to obtain formed sheets.

[0055] 7. Post-processing: UV coating roller coating process, the first UV curing time is 22s, the UV intensity is 125mW / cm², the second UV curing time is 32s, the UV intensity is 155mW / cm², and the high-gloss coating thickness is 0.35mm.

[0056] 8. Quality inspection and warehousing: After passing the quality inspection, the products are sent to the automatic warehousing system for storage.

[0057] Test verification: Quality inspection and testing process 1. Static bending strength test: According to GB / T4897-2015, the sampling size is 20mm×200mm×the thickness of the finished product. The three-point bending method is used for testing. The span is 20 times the thickness of the specimen. The loading speed is 10mm / min. The maximum load is recorded and the static bending strength is calculated. The static bending strength is ≥12.0MPa and is qualified.

[0058] 2. Internal bonding strength test: According to GB / T4897-2015, the sampling size is 50mm×50mm. The upper and lower surfaces of the specimen are bonded to the metal test block with epoxy resin glue. After curing, it is stretched at a speed of 10mm / min using a tensile testing machine. The maximum tensile force is recorded and the internal bonding strength is calculated. The internal bonding strength is ≥0.26MPa and is qualified.

[0059] 3. Water absorption thickness expansion rate test: According to GB / T4897-2015, the sampling size is 50mm×50mm. First, measure the initial thickness of the specimen, then soak the specimen in 20±2℃ distilled water for 24h. After taking it out, wipe the surface of the specimen dry, measure the thickness after water absorption, and calculate the expansion rate. The water absorption thickness expansion rate ≤1.4% is qualified.

[0060] 4. Surface finish test: Use a surface roughness meter to test. Randomly select 5 measuring points on the surface of the specimen, avoiding the edge of the specimen, and measure the Ra value of each measuring point. The Ra value of the high-gloss surface is ≤0.7μm and the Ra value of the ordinary fiber surface is ≤1.8μm to be qualified.

[0061] Sample preparation and specific testing steps: 1. Sample preparation: Five specimens were randomly selected from each of Examples 1-3 and the comparative example. The comparative example was a traditional three-layer particleboard using a secondary pressing fiber layer process. The test samples were prepared according to the requirements of GB / T4897-2015, where the static bending strength specimen size was 20 mm × 200 mm × finished product thickness, the internal bond strength specimen size was 50 mm × 50 mm, the water absorption thickness expansion rate specimen size was 50 mm × 50 mm, and the surface finish specimen size was 100 mm × 100 mm.

[0062] 2. Static flexural strength test: A three-point bending tester is used for testing. The span L = 20 × specimen thickness, in mm, and the loading speed is 10 mm / min. The maximum load P is recorded. The static flexural strength is calculated according to the formula σ = 3PL / (2bh²), where b is the specimen width and h is the specimen thickness.

[0063] 3. Internal bonding strength test: Bond the upper and lower surfaces of the specimen to the metal test block with epoxy resin glue, cure for 24 hours after bonding, and use a tensile testing machine to stretch at a speed of 10mm / min. Record the maximum tension F and calculate the internal bonding strength according to the formula σ=F / (ab), where a and b are the side lengths of the specimen.

[0064] 4. Water absorption thickness expansion rate test: first measure the initial thickness h0 of the specimen, then soak the specimen in 20±2℃ distilled water for 24 hours, take it out and wipe the surface of the specimen dry, measure the thickness h1 after water absorption, and calculate the expansion rate according to the formula Δh=(h1-h0) / h0×100%.

[0065] 5. Surface finish test: Use a surface roughness meter to randomly select 5 measuring points on the surface of the specimen, avoiding the edge of the specimen, measure the Ra value of each measuring point, and take the average Ra value of the 5 measuring points as the final result.

[0066] Test result table:

[0067] As can be seen from the table, the fiber multi-layer particleboard prepared by the process of the present invention has better performance than traditional particleboard in all aspects, and meets the preset quality standards (static bending strength ≥12.0MPa, internal bonding strength ≥0.26MPa, water absorption thickness expansion rate ≤1.4%, high-gloss surface Ra ≤0.7μm, ordinary fiber surface Ra ≤1.8μm), with stable and reliable performance.

[0068] The above-mentioned embodiments only express a certain implementation method of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the attached claims.

Claims

1. A process for preparing a fiber multilayer particleboard, characterized in that: The following steps are involved: S1. Material preparation: preparing wood raw materials and fiber raw materials; the wood raw materials are used to prepare core shavings, sub-surface shavings and fine surface shavings, and the fiber raw materials are wood fibers or plant fibers; S2, fiber preparation: feeding the fiber raw material in step S1 into a grinder for grinding, and screening through a 120-220 mesh screen after grinding to remove impurities and insufficiently ground crude fibers to obtain qualified fiber material; S3. Drying and sorting: S301. Feed the core wood shavings, sub-surface wood shavings and fine surface wood shavings prepared in step S1 into a dryer for drying, respectively, and control the moisture content of the wood shavings after drying to be 1.5-2.8%; S302, sending the qualified fiber material obtained in step S2 into a fiber dryer for drying, and controlling the moisture content of the fiber material after drying to be 1.2-2.5%; S303, screening the dried core shavings, sub-surface shavings and fine surface shavings through a grading screen to remove core shavings with a length of less than 50 mm, sub-surface shavings and fine surface shavings with a length of less than 30 mm; S4, glue application: S401, sizing the core wood shavings: adding isocyanate glue to the dried core wood shavings in an amount of 6-9% based on the dry weight of the core wood shavings, and stirring evenly; S402, sizing the sub-surface wood chips and the fine surface wood chips: adding melamine urea-formaldehyde resin glue to the dried sub-surface wood chips and the fine surface wood chips, respectively, in an amount of 7-12% based on the dry weight of the sub-surface wood chips or the fine surface wood chips, and controlling the moisture content of the wood chips after sizing to be 6-11%, and stirring evenly; S403, sizing the fiber material: adding modified urea-formaldehyde resin glue to the dried qualified fiber material, wherein the modified urea-formaldehyde resin glue comprises 9-13 parts by weight of urea-formaldehyde resin, 1.5-3.5 parts by weight of polyvinyl alcohol, 0.8-1.8 parts by weight of waterproofing agent, and 6-9 parts by weight of distilled water, with the glue amount being 9-13% based on the dry weight of the fiber material, and stirring uniformly; S5. Paving and forming: A paving device is used to continuously pave a multi-layer slab on a conveyor belt at one time. The center of the multi-layer slab is a core layer. A sub-surface layer, a fine surface layer, and a fiber surface layer are symmetrically arranged on the upper and lower sides of the core layer. The fiber surface layer has a thickness of 1.1 to 1.5 mm, the fine surface layer has a thickness of 1.8 to 3.5 mm, the sub-surface layer has a thickness of 3.5 to 5.5 mm, and the core layer has a thickness of 8.5 to 15.5 mm. S6, compression molding: S601, pre-pressing: feeding the multi-layer slab from step S5 into a pre-pressing machine, and pre-pressing for 2.5 to 6 minutes at a pressure of 1.2 to 3.5 MPa and a temperature of 35 to 50° C. to obtain a pre-pressed body; S602, hot pressing: the pre-pressed green body is fed into a continuous flat press at once, and hot pressed for 3.5 to 9 minutes at a pressure of 4.5 to 6.5 MPa and a temperature of 185 to 225°C. During the hot pressing process, the green body density is controlled to be 680 to 780 kg / m³, to obtain a formed plate; S7, post-processing: S701, Sanding: Sand both sides of the hot-pressed sheet to remove surface burrs and uneven areas, and control the thickness deviation of the sheet after sanding to ≤±0.25mm; S702, cutting: according to the finished product size requirements, the sanded plate is cut to length; S703, Surface treatment: Dust and oil removal are carried out on the surface of the cut plate, and UV coating roller coating process is used to make the surface of the plate high glossy; S8, automatic storage: the plate materials processed in step S7 are subjected to quality inspection, and those that pass the inspection are sent to the automatic storage system for classification and storage.

2. The process for preparing a fiber multilayer particleboard according to claim 1, characterized in that: In step S1, the core layer shavings have a length of 120 mm to 160 mm, a width of 15 mm to 35 mm, and a thickness of 0.5 mm to 0.9 mm; the sub-surface shavings and fine surface shavings have a length of 60 mm to 110 mm, a width of 8 mm to 20 mm, and a thickness of 0.3 mm to 0.6 mm.

3. The process for preparing a fiber multilayer particleboard according to claim 1, characterized in that: In step S2, the grinder is a double-disc grinder, and the grinding disc gap is controlled to be 0.15-0.35 mm during grinding, and the grinding speed is 1300-1600 r / min; in step S301, the dryer is a mesh belt dryer, the drying temperature is 105-125°C, and the drying time is 18-28 min; in step S302, the fiber dryer is an air flow dryer, the drying temperature is 85-105°C, and the drying time is 6-12 min.

4. The process for preparing a fiber multilayer particleboard according to claim 1, characterized in that: In step S403, the waterproofing agent is paraffin emulsion, and the solid content of the modified urea-formaldehyde resin glue is 42-47%; in step S4, a double-shaft stirrer is used for stirring, the stirring speed is 350-550 r / min, and the stirring time is 3.5-5.5 min to ensure that the adhesive evenly covers the wood chips or fiber material.

5. The process for preparing a fiber multilayer particleboard according to claim 1, characterized in that: In step S5, the paving speed of the paving system is matched with the feeding speed of the continuous flatbed press and is controlled to be 5.5 to 8.5 m / min.

6. The process for preparing a fiber multilayer particleboard according to claim 1, characterized in that: In step S602, the continuous flat press adopts segmented temperature control, with the temperature of the front section of hot pressing being 185-195°C, the temperature of the middle section being 195-215°C, and the temperature of the back section being 215-225°C.

7. The process for preparing a fiber multilayer particleboard according to claim 1, characterized in that: In step S703, the UV coating roller coating process includes the following steps: S7031, first roller coating of UV primer; S7032, UV curing, curing time 12 to 22 seconds, UV intensity 85 to 125 mW / cm²; S7033, sanding; S7034, secondary roller coating UV topcoat; S7035, UV curing, curing time 22 ~ 32s, UV intensity 125 ~ 155mW / cm², forming a high gloss coating with a thickness of 0.15 ~ 0.35mm.

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